Washing machines perform washing, rinsing, and spin-drying processes using water, detergent, and mechanical force, and remove stains from laundry items placed in the washing tub.
When water is introduced into the bottom of the washing tub of the washing machine, the water is also introduced into an air chamber. The water introduced into the air chamber fills the air chamber at the same level as the water in the washing tub.
The air within the air chamber is compressed by the volume of the water introduced into the air chamber, and the compressed air is transferred to a water level sensor through an air trap. The water level sensor measures the water level in the washing tub according to the pressure of the transferred air.
According to a conventional washing process, the water level of the washing tub is measured at the initial stage of the washing process, and water is supplied or discharged at a necessary level so as to perform the washing process. Alternatively, the water in the washing tub is completely discharged, and water is then resupplied to perform the washing process.
However, when water remaining in the air trap is frozen in the winter season due to a very low temperature around the washing machine, the pressure of air transferred to the water level sensor changes. Therefore, the water level measured by the water level sensor may be different from the actual water level in the washing tub.
When the water level measured by the water level sensor is different from the actual water level in the washing tub, water may not be supplied or discharged at a level adequate to perform the washing process. In this case, the washing process may not be performed properly.
Furthermore, when the water level is measured by the water level sensor incorrectly determines that the washing water level is equal to or higher than the actual washing water level even though no water exists in the washing tub, a heater may begin operating when there is no water in the washing tub. In this case, a fire may occur.
Furthermore, although water is completely discharged and then resupplied, all of the water containing dissolved detergent is discharged when a user powers the washing machine on or off, as occasion demands. Therefore, water and detergent may be wasted.
The above-described configuration is a disclosure of related art for helping with the understanding of the present invention, and does not mean a related art which is widely known in the technical field to which the present invention pertains.